X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fendgame.cpp;h=f59456bdc5adfe6d7c0954ef3bd182e4ee65ad81;hp=01f4101ed8866ce63748d72cd8da177b78a229e1;hb=83631c89cec7f1afd8b97a3e676cd0c12a4e8633;hpb=67375f4693c97fb1321864bb4d143812cd824f9b diff --git a/src/endgame.cpp b/src/endgame.cpp index 01f4101e..f59456bd 100644 --- a/src/endgame.cpp +++ b/src/endgame.cpp @@ -1,7 +1,7 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008 Marco Costalba + Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -25,43 +25,10 @@ #include #include "bitbase.h" +#include "bitcount.h" #include "endgame.h" -//// -//// Constants and variables -//// - -/// Evaluation functions - -// Generic "mate lone king" eval -EvaluationFunction EvaluateKXK(WHITE), EvaluateKKX(BLACK); - -// K and two minors vs K and one or two minors -EvaluationFunction EvaluateKmmKm(WHITE); - -EvaluationFunction EvaluateKBNK(WHITE), EvaluateKKBN(BLACK); // KBN vs K -EvaluationFunction EvaluateKPK(WHITE), EvaluateKKP(BLACK); // KP vs K -EvaluationFunction EvaluateKRKP(WHITE), EvaluateKPKR(BLACK); // KR vs KP -EvaluationFunction EvaluateKRKB(WHITE), EvaluateKBKR(BLACK); // KR vs KB -EvaluationFunction EvaluateKRKN(WHITE), EvaluateKNKR(BLACK); // KR vs KN -EvaluationFunction EvaluateKQKR(WHITE), EvaluateKRKQ(BLACK); // KQ vs KR -EvaluationFunction EvaluateKBBKN(WHITE), EvaluateKNKBB(BLACK); // KBB vs KN - - -/// Scaling functions - -ScalingFunction ScaleKBPK(WHITE), ScaleKKBP(BLACK); // KBP vs K -ScalingFunction ScaleKQKRP(WHITE), ScaleKRPKQ(BLACK); // KQ vs KRP -ScalingFunction ScaleKRPKR(WHITE), ScaleKRKRP(BLACK); // KRP vs KR -ScalingFunction ScaleKRPPKRP(WHITE), ScaleKRPKRPP(BLACK); // KRPP vs KRP -ScalingFunction ScaleKPsK(WHITE), ScaleKKPs(BLACK); // King and pawns vs king -ScalingFunction ScaleKBPKB(WHITE), ScaleKBKBP(BLACK); // KBP vs KB -ScalingFunction ScaleKBPKN(WHITE), ScaleKNKBP(BLACK); // KBP vs KN -ScalingFunction ScaleKNPK(WHITE), ScaleKKNP(BLACK); // KNP vs K -ScalingFunction ScaleKPKPw(WHITE), ScaleKPKPb(BLACK); // KPKP - - //// //// Local definitions //// @@ -137,7 +104,7 @@ namespace { /// attacking side a bonus for driving the defending king towards the edge /// of the board, and for keeping the distance between the two kings small. template<> -Value EvaluationFunction::apply(const Position& pos) { +Value EvaluationFunction::apply(const Position& pos) const { assert(pos.non_pawn_material(weakerSide) == Value(0)); assert(pos.piece_count(weakerSide, PAWN) == Value(0)); @@ -163,7 +130,7 @@ Value EvaluationFunction::apply(const Position& pos) { /// Mate with KBN vs K. This is similar to KX vs K, but we have to drive the /// defending king towards a corner square of the right color. template<> -Value EvaluationFunction::apply(const Position& pos) { +Value EvaluationFunction::apply(const Position& pos) const { assert(pos.non_pawn_material(weakerSide) == Value(0)); assert(pos.piece_count(weakerSide, PAWN) == Value(0)); @@ -192,7 +159,7 @@ Value EvaluationFunction::apply(const Position& pos) { /// KP vs K. This endgame is evaluated with the help of a bitbase. template<> -Value EvaluationFunction::apply(const Position& pos) { +Value EvaluationFunction::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == Value(0)); assert(pos.non_pawn_material(weakerSide) == Value(0)); @@ -240,7 +207,7 @@ Value EvaluationFunction::apply(const Position& pos) { /// far advanced with support of the king, while the attacking king is far /// away. template<> -Value EvaluationFunction::apply(const Position& pos) { +Value EvaluationFunction::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 0); @@ -297,7 +264,7 @@ Value EvaluationFunction::apply(const Position& pos) { /// KR vs KB. This is very simple, and always returns drawish scores. The /// score is slightly bigger when the defending king is close to the edge. template<> -Value EvaluationFunction::apply(const Position& pos) { +Value EvaluationFunction::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 0); @@ -313,7 +280,7 @@ Value EvaluationFunction::apply(const Position& pos) { /// KR vs KN. The attacking side has slightly better winning chances than /// in KR vs KB, particularly if the king and the knight are far apart. template<> -Value EvaluationFunction::apply(const Position& pos) { +Value EvaluationFunction::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 0); @@ -337,7 +304,7 @@ Value EvaluationFunction::apply(const Position& pos) { /// for the defending side in the search, this is usually sufficient to be /// able to win KQ vs KR. template<> -Value EvaluationFunction::apply(const Position& pos) { +Value EvaluationFunction::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == QueenValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 0); @@ -356,13 +323,13 @@ Value EvaluationFunction::apply(const Position& pos) { } template<> -Value EvaluationFunction::apply(const Position& pos) { +Value EvaluationFunction::apply(const Position& pos) const { assert(pos.piece_count(strongerSide, BISHOP) == 2); assert(pos.non_pawn_material(strongerSide) == 2*BishopValueMidgame); assert(pos.piece_count(weakerSide, KNIGHT) == 1); assert(pos.non_pawn_material(weakerSide) == KnightValueMidgame); - assert(pos.pawns() == EmptyBoardBB); + assert(pos.pieces(PAWN) == EmptyBoardBB); Value result = BishopValueEndgame; Square wksq = pos.king_square(strongerSide); @@ -376,16 +343,23 @@ Value EvaluationFunction::apply(const Position& pos) { result += Value(square_distance(bksq, nsq) * 32); // Bonus for restricting the knight's mobility - result += Value((8 - count_1s_max_15(pos.piece_attacks(nsq))) * 8); + result += Value((8 - count_1s_max_15(pos.attacks_from(nsq))) * 8); return (strongerSide == pos.side_to_move() ? result : -result); } + +/// K and two minors vs K and one or two minors or K and two knights against +/// king alone are always draw. template<> -Value EvaluationFunction::apply(const Position &pos) { +Value EvaluationFunction::apply(const Position&) const { return Value(0); } +template<> +Value EvaluationFunction::apply(const Position&) const { + return Value(0); +} /// KBPKScalingFunction scales endgames where the stronger side has king, /// bishop and one or more pawns. It checks for draws with rook pawns and a @@ -393,7 +367,7 @@ Value EvaluationFunction::apply(const Position &pos) { /// returned. If not, the return value is SCALE_FACTOR_NONE, i.e. no scaling /// will be used. template<> -ScaleFactor ScalingFunction::apply(const Position& pos) { +ScaleFactor ScalingFunction::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); assert(pos.piece_count(strongerSide, BISHOP) == 1); @@ -402,7 +376,7 @@ ScaleFactor ScalingFunction::apply(const Position& pos) { // No assertions about the material of weakerSide, because we want draws to // be detected even when the weaker side has some pawns. - Bitboard pawns = pos.pawns(strongerSide); + Bitboard pawns = pos.pieces(PAWN, strongerSide); File pawnFile = square_file(pos.piece_list(strongerSide, PAWN, 0)); // All pawns are on a single rook file ? @@ -419,7 +393,6 @@ ScaleFactor ScalingFunction::apply(const Position& pos) { // The bishop has the wrong color, and the defending king is on the // file of the pawn(s) or the neighboring file. Find the rank of the // frontmost pawn. - Rank rank; if (strongerSide == WHITE) { @@ -448,7 +421,7 @@ ScaleFactor ScalingFunction::apply(const Position& pos) { /// It tests for fortress draws with a rook on the third rank defended by /// a pawn. template<> -ScaleFactor ScalingFunction::apply(const Position& pos) { +ScaleFactor ScalingFunction::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == QueenValueMidgame); assert(pos.piece_count(strongerSide, QUEEN) == 1); @@ -459,12 +432,12 @@ ScaleFactor ScalingFunction::apply(const Position& pos) { Square kingSq = pos.king_square(weakerSide); if ( relative_rank(weakerSide, kingSq) <= RANK_2 && relative_rank(weakerSide, pos.king_square(strongerSide)) >= RANK_4 - && (pos.rooks(weakerSide) & relative_rank_bb(weakerSide, RANK_3)) - && (pos.pawns(weakerSide) & relative_rank_bb(weakerSide, RANK_2)) - && (pos.piece_attacks(kingSq) & pos.pawns(weakerSide))) + && (pos.pieces(ROOK, weakerSide) & relative_rank_bb(weakerSide, RANK_3)) + && (pos.pieces(PAWN, weakerSide) & relative_rank_bb(weakerSide, RANK_2)) + && (pos.attacks_from(kingSq) & pos.pieces(PAWN, weakerSide))) { Square rsq = pos.piece_list(weakerSide, ROOK, 0); - if (pos.pawn_attacks(strongerSide, rsq) & pos.pawns(weakerSide)) + if (pos.attacks_from(rsq, strongerSide) & pos.pieces(PAWN, weakerSide)) return ScaleFactor(0); } return SCALE_FACTOR_NONE; @@ -479,7 +452,7 @@ ScaleFactor ScalingFunction::apply(const Position& pos) { /// It would also be nice to rewrite the actual code for this function, /// which is mostly copied from Glaurung 1.x, and not very pretty. template<> -ScaleFactor ScalingFunction::apply(const Position &pos) { +ScaleFactor ScalingFunction::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 1); @@ -597,7 +570,7 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { /// single pattern: If the stronger side has no pawns and the defending king /// is actively placed, the position is drawish. template<> -ScaleFactor ScalingFunction::apply(const Position &pos) { +ScaleFactor ScalingFunction::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == RookValueMidgame); assert(pos.piece_count(strongerSide, PAWN) == 2); @@ -636,14 +609,14 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { /// against king. There is just a single rule here: If all pawns are on /// the same rook file and are blocked by the defending king, it's a draw. template<> -ScaleFactor ScalingFunction::apply(const Position &pos) { +ScaleFactor ScalingFunction::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == Value(0)); assert(pos.piece_count(strongerSide, PAWN) >= 2); assert(pos.non_pawn_material(weakerSide) == Value(0)); assert(pos.piece_count(weakerSide, PAWN) == 0); - Bitboard pawns = pos.pawns(strongerSide); + Bitboard pawns = pos.pieces(PAWN, strongerSide); // Are all pawns on the 'a' file? if ((pawns & ~FileABB) == EmptyBoardBB) @@ -682,7 +655,7 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { /// it's a draw. If the two bishops have opposite color, it's almost always /// a draw. template<> -ScaleFactor ScalingFunction::apply(const Position &pos) { +ScaleFactor ScalingFunction::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); assert(pos.piece_count(strongerSide, BISHOP) == 1); @@ -721,9 +694,9 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { else { Bitboard ray = ray_bb(pawnSq, (strongerSide == WHITE)? SIGNED_DIR_N : SIGNED_DIR_S); - if (ray & pos.kings(weakerSide)) + if (ray & pos.pieces(KING, weakerSide)) return ScaleFactor(0); - if( (pos.piece_attacks(weakerBishopSq) & ray) + if( (pos.attacks_from(weakerBishopSq) & ray) && square_distance(weakerBishopSq, pawnSq) >= 3) return ScaleFactor(0); } @@ -732,12 +705,86 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { } +/// KBPPKBScalingFunction scales KBPP vs KB endgames. It detects a few basic +/// draws with opposite-colored bishops. +template<> +ScaleFactor ScalingFunction::apply(const Position& pos) const { + + assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); + assert(pos.piece_count(strongerSide, BISHOP) == 1); + assert(pos.piece_count(strongerSide, PAWN) == 2); + assert(pos.non_pawn_material(weakerSide) == BishopValueMidgame); + assert(pos.piece_count(weakerSide, BISHOP) == 1); + assert(pos.piece_count(weakerSide, PAWN) == 0); + + Square wbsq = pos.piece_list(strongerSide, BISHOP, 0); + Square bbsq = pos.piece_list(weakerSide, BISHOP, 0); + + if (square_color(wbsq) == square_color(bbsq)) + // Not opposite-colored bishops, no scaling + return SCALE_FACTOR_NONE; + + Square ksq = pos.king_square(weakerSide); + Square psq1 = pos.piece_list(strongerSide, PAWN, 0); + Square psq2 = pos.piece_list(strongerSide, PAWN, 1); + Rank r1 = square_rank(psq1); + Rank r2 = square_rank(psq2); + Square blockSq1, blockSq2; + + if (relative_rank(strongerSide, psq1) > relative_rank(strongerSide, psq2)) + { + blockSq1 = psq1 + pawn_push(strongerSide); + blockSq2 = make_square(square_file(psq2), square_rank(psq1)); + } + else + { + blockSq1 = psq2 + pawn_push(strongerSide); + blockSq2 = make_square(square_file(psq1), square_rank(psq2)); + } + + switch (file_distance(psq1, psq2)) + { + case 0: + // Both pawns are on the same file. Easy draw if defender firmly controls + // some square in the frontmost pawn's path. + if ( square_file(ksq) == square_file(blockSq1) + && relative_rank(strongerSide, ksq) >= relative_rank(strongerSide, blockSq1) + && square_color(ksq) != square_color(wbsq)) + return ScaleFactor(0); + else + return SCALE_FACTOR_NONE; + + case 1: + // Pawns on neighboring files. Draw if defender firmly controls the square + // in front of the frontmost pawn's path, and the square diagonally behind + // this square on the file of the other pawn. + if ( ksq == blockSq1 + && square_color(ksq) != square_color(wbsq) + && ( bbsq == blockSq2 + || (pos.attacks_from(blockSq2) & pos.pieces(BISHOP, weakerSide)) + || rank_distance(r1, r2) >= 2)) + return ScaleFactor(0); + else if ( ksq == blockSq2 + && square_color(ksq) != square_color(wbsq) + && ( bbsq == blockSq1 + || (pos.attacks_from(blockSq1) & pos.pieces(BISHOP, weakerSide)))) + return ScaleFactor(0); + else + return SCALE_FACTOR_NONE; + + default: + // The pawns are not on the same file or adjacent files. No scaling. + return SCALE_FACTOR_NONE; + } +} + + /// KBPKNScalingFunction scales KBP vs KN endgames. There is a single rule: /// If the defending king is somewhere along the path of the pawn, and the /// square of the king is not of the same color as the stronger side's bishop, /// it's a draw. template<> -ScaleFactor ScalingFunction::apply(const Position &pos) { +ScaleFactor ScalingFunction::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == BishopValueMidgame); assert(pos.piece_count(strongerSide, BISHOP) == 1); @@ -764,7 +811,7 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { /// If the pawn is a rook pawn on the 7th rank and the defending king prevents /// the pawn from advancing, the position is drawn. template<> -ScaleFactor ScalingFunction::apply(const Position &pos) { +ScaleFactor ScalingFunction::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == KnightValueMidgame); assert(pos.piece_count(strongerSide, KNIGHT) == 1); @@ -794,7 +841,7 @@ ScaleFactor ScalingFunction::apply(const Position &pos) { /// advanced and not on a rook file; in this case it is often possible to win /// (e.g. 8/4k3/3p4/3P4/6K1/8/8/8 w - - 0 1). template<> -ScaleFactor ScalingFunction::apply(const Position &pos) { +ScaleFactor ScalingFunction::apply(const Position& pos) const { assert(pos.non_pawn_material(strongerSide) == Value(0)); assert(pos.non_pawn_material(weakerSide) == Value(0));